Goals: Deep Impact's primary mission was to probe beneath the surface of a comet. The spacecraft delivered a special impactor into the path of Tempel 1 to reveal never before seen materials and provide clues about the internal composition and structure of a comet.

Accomplishments: After almost nine years in space that included an unprecedented 4th of July impact and subsequent flyby of a comet, an additional comet flyby, and the return of approximately 500,000 images of celestial objects, NASA's Deep Impact mission ended in September 2013.

Deep Impact, history's most traveled deep-space comet hunter, provided many significant results for the science community. Here are the mission team's top five:

First determination that a comet's surface layer (few to 10 meters or so) is very porous (greater than 75 percent empty space)

First direct evidence showing chemical diversity of outgassing associated with different parts of the cometary nucleus

Discovered that hyperactive comets (5-10 percent of all comets) are driven by carbon dioxide and that the observed excess water is from icy grains in the coma. The processes of hyperactive comets are very different from those in normal comets.

Observations led to re-thinking where in the solar system comets formed. Contrary to all thinking, for the last half century, the Jupiter family comets must have formed closer to the sun than did the Oort cloud comets.

Enabled the subsequent exciting results from the Stardust NExT mission that changes theories on how comets evolve.